1. Technical Field
The invention relates to optical technology, and particularly to an aperture stop and manufacturing method thereof.
2. Description of Related Art
Referring to FIG. 6, an optical lens module 10 has a first lens L1, a second lens L2 and an aperture stop St. The aperture stop St is disposed between the first lens L1 and the second lens L2, and the optical centers of the aperture stop St, the first lens L1 and the second lens L2 are aligned. Given that total thickness of the optical lens module 10 is constant, costs of the first lens L1 and the second lens L2 are affected by the thickness of the aperture stop St accordingly. For example, if the aperture stop St is very thick, the thickness of the first lens L1 and the second lens L2 must be reduced. Shapes of the first lens L1 and the second lens L2, however, create difficultly in the manufacturing process. Further, as the volume of the optical lens module 10 reduced, there is a requirement for the thickness of the first lens L1 and the second lens L2 to be reduced accordingly.
Thickness of the aperture stop St is generally 0.029 mm. Further reduction of the thickness of the aperture stop St cannot be achieved, due to the limitations of the constituent glass or plastic material, whereby breakage or deformation are likely in the manufacturing process.
What is needed, therefore, is an aperture stop and manufacturing method thereof achieving desired thinness with strength and integrity maintained.